4 ms·

0.1c would make this a 220 year journey each way. So what you're really saying is: no, it's not possible reach these planets in our lifetime.

cryptoz 13y ago
I was imagining we would also be researching biology at the same time, and would be able to live that long or sleep during the trip. If we're able to move at .1c I can't imagine we'll still die as quickly as people born in 1900.
- rch 13y ago
  I saw a presentation on this at a DARPA meeting a couple years ago. It is exactly the kind of thing that could make long-term space travel possible. http://www.wired.com/dangerroom/2007/12/zombie-mouse-ma/ http://www.wired.com/dangerroom/2007/12/zombie-mouse-ma/
- chc 13y ago
  There's a huge gap between "20 years from now, we won't die as quickly as people born in 1900" and "20 years from now, people will live four times as long as they do in 2013." The former is quite likely. The latter is pretty far out there.
DougWebb 13y ago
Is that fast enough for relativistic effects on-board? It might be 220 years for those left behind, but for the people on the ship it might be less than a lifetime. They'd probably still have to raise children on the way to take care of the exploring when they got there.
- cgore 13y ago
  218 years, instead of 220. http://www.wolframalpha.com/input/?i=time+dilation+calculator&a=*FS-_**RelativisticTimeDilationFormula.to-.*RelativisticTimeDilationFormula.t-.*RelativisticTimeDilationFormula.v--&f2=220+year&x=0&y=0&f=RelativisticTimeDilationFormula.t_220+year&f3=0.1+c&f=RelativisticTimeDilationFormula.v_0.1+c http://www.wolframalpha.com/input/?i=time+dilation+calculato...
- lmm 13y ago
  There are no substantial relativistic effects at 0.1c; the time dilation factor is sqrt(c^2 - v^2), so about 0.995 in this case.
yohann305 13y ago
you have to take into account that the closer you get to light speed, the slower time goes. In other words, people on the space ship may age slower, meaning that 220 years may be a lot less to them. What is the equivalent of 1 earth year on a spaceship going at 0.1c, that is the question.
- gus_massa 13y ago
  The relativistic correction is Time_on_Ship = Time_on_Earth * (1 - (v/c)^2)^(1/2) If v <<c we can use the Taylor approximation Time_on_Ship =~ Time_on_Earth * (1 - (1/2) (v/c)^2) Distributing Time_on_Ship =~ Time_on_Earth - Time_on_Earth (1/2) (v/c)^2 With the current number, assuming instant acceleration to simplify the calculations: Time_on_Earth = (22/.1) Time difference =~ (22/.1) (1/2) * .1^2 years = 1.10 years The important detail is that for small speeds, the correction is quadratic, so the difference is small unless the speed is very close to c. In this case the correction is only 0.5%.
  - yohann305 13y ago
    Good stuff! Thx Gus
- johngalt 13y ago
  The Lorentz factor doesn't really make an appreciable difference until you get much closer to c. For instance cutting the trip time in half would require .866c. .99c would cut the trip down to ~30years.
  - shawabawa3 13y ago
    > .99c would cut the trip down to ~30years. Surely you forgot to take into account that increasing the speed shortens the trip as well as dilating time? Travelling at 0.99c would take 22 years to reach that from an observer's point of view, which would be 3 years for the people on board
    - johngalt 13y ago

cryptoz 13y ago

I was imagining we would also be researching biology at the same time, and would be able to live that long or sleep during the trip. If we're able to move at .1c I can't imagine we'll still die as quickly as people born in 1900.

rch 13y ago
I saw a presentation on this at a DARPA meeting a couple years ago. It is exactly the kind of thing that could make long-term space travel possible. http://www.wired.com/dangerroom/2007/12/zombie-mouse-ma/ http://www.wired.com/dangerroom/2007/12/zombie-mouse-ma/
chc 13y ago
There's a huge gap between "20 years from now, we won't die as quickly as people born in 1900" and "20 years from now, people will live four times as long as they do in 2013." The former is quite likely. The latter is pretty far out there.

DougWebb 13y ago

Is that fast enough for relativistic effects on-board? It might be 220 years for those left behind, but for the people on the ship it might be less than a lifetime. They'd probably still have to raise children on the way to take care of the exploring when they got there.

cgore 13y ago
218 years, instead of 220. http://www.wolframalpha.com/input/?i=time+dilation+calculator&a=*FS-_**RelativisticTimeDilationFormula.to-.*RelativisticTimeDilationFormula.t-.*RelativisticTimeDilationFormula.v--&f2=220+year&x=0&y=0&f=RelativisticTimeDilationFormula.t_220+year&f3=0.1+c&f=RelativisticTimeDilationFormula.v_0.1+c http://www.wolframalpha.com/input/?i=time+dilation+calculato...
lmm 13y ago
There are no substantial relativistic effects at 0.1c; the time dilation factor is sqrt(c^2 - v^2), so about 0.995 in this case.

yohann305 13y ago

you have to take into account that the closer you get to light speed, the slower time goes. In other words, people on the space ship may age slower, meaning that 220 years may be a lot less to them. What is the equivalent of 1 earth year on a spaceship going at 0.1c, that is the question.

gus_massa 13y ago
The relativistic correction is Time_on_Ship = Time_on_Earth * (1 - (v/c)^2)^(1/2) If v <<c we can use the Taylor approximation Time_on_Ship =~ Time_on_Earth * (1 - (1/2) (v/c)^2) Distributing Time_on_Ship =~ Time_on_Earth - Time_on_Earth (1/2) (v/c)^2 With the current number, assuming instant acceleration to simplify the calculations: Time_on_Earth = (22/.1) Time difference =~ (22/.1) (1/2) * .1^2 years = 1.10 years The important detail is that for small speeds, the correction is quadratic, so the difference is small unless the speed is very close to c. In this case the correction is only 0.5%.
- yohann305 13y ago
  Good stuff! Thx Gus
johngalt 13y ago
The Lorentz factor doesn't really make an appreciable difference until you get much closer to c. For instance cutting the trip time in half would require .866c. .99c would cut the trip down to ~30years.
- shawabawa3 13y ago
  > .99c would cut the trip down to ~30years. Surely you forgot to take into account that increasing the speed shortens the trip as well as dilating time? Travelling at 0.99c would take 22 years to reach that from an observer's point of view, which would be 3 years for the people on board
  - johngalt 13y ago